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气体驱替煤层气技术是近年来发展起来的具有温室气体减排和提高煤层气采收率双赢效果的新兴技术,相关研究受到世界主要发达国家的广泛重视。对于温室气体减排的压力,发达国家的研究主要着眼于该技术在高渗透、不可采煤层中的应用,注入气体主要为CO2,目的是尽可能多地封存CO2,同时提高煤层气采收率。目前,国内在这方面的研究刚刚起步。国内煤层具有渗透率普遍较低、不开采煤层与要开采煤层难以界定的特点,注CO2气体驱替煤层气在这种煤层中的可行性值得商榷。针对国内煤层特点和煤矿瓦斯抽采率低的现状,建议采用富N2混合气体驱替煤层气技术,以提高煤层气产采收率。通过理论分析、数值模拟和现场试验研究分析了实施混合气体驱替煤层气技术的可行性。研究结果表明,混合气体驱替煤层气技术适用于国内低渗透、可开采煤层,可以提高煤层气采收率和单产量。
Gas-displacing CBM technology is an emerging technology developed in recent years with a win-win result of reducing greenhouse gas emissions and improving CBM recovery efficiency. The research has attracted wide attention from major developed countries in the world. For the pressure of greenhouse gas emission reduction, the research of developed countries mainly focuses on the application of this technology in high-permeability and non-exploitable coal seam. The main injection gas is CO2, so as to sequester CO2 as much as possible while improving CBM recovery rate. At present, the domestic research in this area has just started. The permeability of coal seams in our country is generally low, so the feasibility of displacing CBM in this kind of coal seam with CO2 gas is worth discussing. In view of the characteristics of domestic coal seams and the low gas drainage rate in coal mines, it is suggested that rich N2 mixed gas be used to displace CBM technology so as to improve CBM recovery. Through the theoretical analysis, numerical simulation and field test, the feasibility of implementing mixed gas to displace CBM technology was analyzed. The results show that the technology of mixed gas displacing CBM can be applied to domestic low-permeability and exploitable coal seams, which can improve CBM recovery and single-output.